Any brand that is broken. Or unplugged.
Google this- air conditioning window decibel . There were a lot of generalities, but no listing I could find in the amount of time I wanted to spend looking.
There is nothing called quitest air conditioners as no matter how well-made or of whichever brand they are they do make a little noise.
There is no such air conditioning unit that can give you the quietest, but according to some sites split air conditioners are more quiet than the other models.
Other people asked questions on similar topics, check out the answers they received:
Other people asked questions on various topics, and are still waiting for answer. Would be great if you can take a sec and answer them